Air-supported thread overrun roller

ABSTRACT

In textile apparatus, an air-supported thread overrun roller of tubular shell construction rotatably carried on a hollow shaft segment of enlarged diameter having radial openings to direct compressed air into a small annular bearing gap, thereby providing an air-cushioned bearing for the shell, an annular face plate partly enclosing each end of the tubular shell and containing a plurality of air outlet channels extending approximately parallel to the shell and obliquely to the shell axis of rotation. The thread overrun roller is especially useful in the high speed transport of threads, yarns or the like in stretching, twisting and other textile processing operations.

United States Patent [191 Bauer et al.

[ 51 July 17, 1973 1 AIR-SUPPORTED THREAD OVERRUN ROLLER [75] Inventors:Karl Bauer; Manfred Mayer; Peter Illg, all of Remscheid; Bernd Schimmel,Remscheid-Luttringhausen, all of Germany [73] Assignee: Barmag BarmerMashinenfabrik Aktiengesellschaft, Wuppertal, Germany 22 Filed: July 6,1972 21 Appl. No: 269,457

[30] Foreign Application Priority Data Aug. 9, 1971 Germany... ..P 21 34247.2

[52] US. Cl. 226/194, 308/DIG. l [51] Int. Cl B65h 17/20 [58] Field ofSearch 226/97, 95, 194;

308/D1G. 1; 242/157 R [56] References Cited UNITED STATES PATENTS3,063,041 11/1962 Quade et al. 308/D1G. 1

Primary Examiner-Allen N. Knowles Attorney.lohn H. Shurtleff {5 7]ABSTRACT In textile apparatus, an air-supported thread overrun roller oftubular shell construction rotatably carried on a hollow shaft segmentof enlarged diameter having radial openings to direct compressed airinto a small annular bearing gap, thereby providing an air-cushionedbearing for the shell, an annular face plate partly enclosing each endof the tubular shell and containing a plurality of air outlet channelsextending approximately parallel to the shell and obliquely to the shellaxis of rotation. The thread overrun roller is especially useful in thehigh speed transport of threads, yarns or the like in stretching,twisting and other textile processing operations.

6 Claims, 4 Drawing Figures Patented July 17, 1973 3,746,233

FIG. I 7

AIR-SUPPORTED THREAD OVERRUN ROLLER The invention relates generally toan air-supported or air-cushioned thread overrun roller, in which atubular roller shell is turnably carried on an axle which has an axialair feed channel and, in the bearing zone of the roller shell, also hasradial openings through which the compressed air passes into the bearinggap between the axle and the inner wall of the roller shell.

By thread overrun rollers one generally means those rollers on a textilemachine or apparatus which are driven by the running thread itself.There are known air-supported thread overrun rollers which are suitedespecially for use in thread treatment devices for synthetic threads,for example, for heated stretching or drawing, heat fixing and the like.In a known airsupported overrun roller, compressed air is suppliedthrough a fixed pivot pin or axle and then passes through the porousstructure of a sintered metal sleeve surrounding the axle into thebearing gap. However, where one uses very high turning rates of thedriven roller (for example on the order of 30,000 rpm or more) asbrought about by correspondingly high thread speeds, such revolvingrollers are no longer capable of meeting the requirements of textilemachines operating at such high thread running speeds. For example,thread breakage occurs frequently, especially in the initial applicationof the thread in starting the roller when the undriven thread overrunroller must be accelerated by the running thread. Furthermore, thereexists the difiiculty of achieving proper axial seating of the roller.Where this is not assured, there is the danger that the overrun rollermay shift axially and thereby come into sliding contact with otherbearing members to exert an undesirable braking effect. For this reason,typical airsuspension or air-cushioning bearings are unsuited for anoverrun roller as is known, for example, according to German Pat. No.842,877 for 'an air-supported belt pulley wherein compressed air issupplied to the bearing zone through an axial bore in a fixed shaft andthe waste air is then drawn off through a second axial bore in the sameshaft. in this bearing system, an axial stabilization of theair-suspended or air-cushioned roller is not assured.

One object of the present invention is to provide an air-supportedoverrun roller for use in textile apparatus in such a way that thethread or yarn is relieved of undesirable tension, especially during theinitial application of the thread, by providing means for acceleratingthe overrun roller in the starting phase. Moreover, it is also an objectof the invention to achieve a stabilization of the axial position of therotating roller member driven by the running thread. Yet another objectof the invention is to provide means to control and/or vary the airpressure supplied to the overrun roller in order to obtain a moreefficient and effective operation. Other objects and advantages of theinvention will become more apparent upon consideration of the followingdetailed specification.

It has now been found, in accordance with the invention, that suchobjects can be achieved in textile apparatus by means of anair-supported thread overrun roller which comprises a hollow tubularroller shell adapted to be rotatably driven by a transported thread,axle means to carry said roller shell including a shaft segment havingan inlet conduit for compressed air extending axially into said rollershell and a hollow cylindrical segment of enlarged diameter connected tosaid shaft segment so as to extend axially between the two ends of saidroller shell and to provide a compressed air chamber fittingconcentrically within said roller shell with a small annular bearing gaptherebetween, the cylindrical wall of said enlarged segment havingradial openings to release compressed air into said bearing gap, and anannular face plate on said roller shell at either end thereof with theinner diameter of the face plate being smaller than the outer diameterof said enlarged axle segment, each face plate having a plurality of airoutlet channels approximately parallel to the roller shell and extendingobliquely to the axis of rotation of the shell, said channels beingarranged at regular intervals on a circle concentric to the axis ofrotation of the shell.

This particular structure of the thread overrun roller and itsair-cushioned bearing means has the consequence that the air emerginglaterally from the circumferential or narrow annular bearing gapthereupon flows obliquely to the axis of rotation through the airoutletchannels or openings ofthe face plates. in this escape of the compressedair, it undergoes such a deflection that an active force componentarises preferably in tangential direction at the roller circumference,thereby yielding a positive drive moment for the roller completely apartfrom the drive imparted by the running thread. The compressed airadvantageously exerts two functions simultaneously. In addition to itsbasic function of assuring a very nearly frictionless suspension orair-cushioning of the roller shell, especially in the initial startingof the machine, the compressed air also has the function of providing amajor or even substantial portion of the total drive force for rotatingthe roller shell. Accordingly, the constituent of the total accelerationmoment to be contributed by the running thread is now only very slightso that the danger of thread breakage is virtually completelyeliminated, even for threads having a fine denier or yarn size. The timerequired for initially applying or starting the overrun of the thread,moreover, is thereby considerably shortened.

A preferred feature of the invention resides in providing a structurewherein the diameter of the circle on which the oblique airoutletchannels lie or upon which these channels are centered cross-sectionallyis equal to or very nearly equal to the mean diameter of the bearing gapbetween the axle and the inner wall of the roller shell. Furthermore, itis advantageous for the axle enlargement in the bearing zone of theroller shell to exhibit axially directed openings through its end walls,the compressed air passing through these openings into a gap spacebetween the inner side of the face plates of the roller shell and theoutwardly facing surfaces of the end walls of the enlarged segment ofthe axle.

Because the path of the compressed air to the oblique outlet channels isthe shortest possible in emerging from the bearing gap, a relativelylarge proportion of the energy resulting from the released air isutilized for the drive of the roller. Furthermore, this preferredconstruction prevents any suction formation between the face plates ofthe roller shell and the enlarged axle, and an air stream is generatedradially in the small circular end gap spaces so as to ensure a fullstabilization of the axial position of the roller shell.

To increase the efiiciency of the device, an especially advantageous andpreferred embodiment is one in which the air outlet channels in eachannular face plate follow a curved path, such that these channels andtheir intervening bridges, lands or fillets are curved in scoop form inthe manner of the blades of an axial turbine.

In the drawings the invention is partly schematically represented by twodifferent embodiments of the roller device constructed according to theinvention.

FIG. 1 is a longitudinal section through the axis of rotation of thethread overrun roller;

FIG. 2 is a partial plan view taken from FIG. 1 to show partiallysectioned end zones of the thread overrun roller;

FIG. 3 is a perspective view of another embodiment of a thread overrunroller with part of one end broken open; and

FIG. 4 is a schematic representation of means for supplying andcontrolling the pressure of the air introduced into the pressure chamberof the thread overrun roller.

The fixed axle or shaft mounted in the frame 1 of a textile machine orthread treating apparatus according to FIGS. 1 and 4, is enlarged indiameter along one segment located in the bearing zone inside the rolleras compared with respect to its adjoining segment or segments protrudingaxially from the roller, so that a pressure chamber 2 is provided intowhich there issues the compressed air feed conduit 3. From the pressurechamber 2, the radial bores 4 lead into a small annular bearing gap 5formed between the enlarged segment 6 of the fixed axle l and the innerwall of the rotatably positioned tubular roller shell 7. In addition tothe radial bores 4 there is also provided a number of axial bores 16which also lead compressed air out of the pressure chamber 2 at eitherenclosed end.

Face plates 8 and 9 are permanently joined at each end to the rollershell 7 and have axial central bores 10 and 11 to accommodatetheprotruding segment of a fixed axle l at one or both ends. The airoutlet channels 12 and 13 in these face plates run parallel to the outercircumferential surface of the roller shell 7 and according to FIG. 1are schematically shown as being parallel to the axis of rotation but infact, according to the plan view of FIG. 2, these outlet channels extendobliquely to the axis of rotation..

According to the embodiment of FIG. 3, the lands, bridges or fillets 15left between the air outlet channels 14 are constructed along curvedlines in scoop or vanelike form in the fashion of the blades of an axialturbine. Through this construction, the force component of thecompressed air acting in axial direction to the circumference of theroller is increased.

The manner in which rollers can be carried by means of a radial airsuspension is generally known. In the airsupported thread overrun rolleraccording to the invention,'the compressed air is conducted through thefeed conduit 3 of fixed axle 1 into the pressure chamber 2. Anothernon-illustrated embodiment of the invention can include fixed axles thatprotrude from each end of the roller and are secured on both sides tothe machine frame. The compressed air supplied to the pressure chamber 2can emerge both through the radially directed bores 4 and also throughthe axially directed bores 16. The air emerging through the bores 4forms an air layer between the axle segment 6 and the roller shell 7,this air layer flowing in both circumferential and axial direction. Thislayer thereby acts as a cushion exerting a radial outward force evenlyaround the entire circumference to maintain the shell 7 in a balancedconcentric position on the enlarged axle 6. The air emerging from thislayer in the bearing gap 5 then flows obliquely out of the rollerthrough the air outlet openings or channels l2, 13 or 14. The componentof recoil force generated by the obliquely emerging air, i.e. a recoilforce active in tangential direction to the circumference of the rollershell, drives the roller in the direction of arrow D. The direction ofthe emerging air is indicated by arrows L.

The air emerging through the axial bores 16 in the end walls of chamber2 stabilizes the roller in its axial position by another air layer whichprevents a contact or rubbing of the face plates 8 and 9 along theirinner surfaces on the corresponding oppositely facing surfaces at theends of the axle segment 6. This second air layer formed in the gapspace 5' at each end of the axle segment 6 is in a plane perpendicularto the axis of rotation and is preferably somewhat narrower than thebearing gap 5 and/or provided with fewer openings 16 compared to radialopenings 4 so that most of the compressed air flows axially out throughthe channels 12. In general, both concentric centering and axialpositioning tend to be self-balancing in this roller device.

In textile machines with a large number of such airsupported threadoverrun rollers, the amount of air to be furnished by a compressed airsource can be quite considerable. In the case of the high turning ratespresent during the normal thread driven operation of the machine, it wasfound however that such a large dynamically generated driving force iscreated by the contacting thread for the rollers, that it is actuallypossible to dispense with the statically generated driving force ofcompressed air. Thereby, a supply of compressed air during the normaloperation became fundamentally unnecessary. On the other hand, in orderto guarantee a stabilization of the axial position of the thread overrunroller even in this normal operating phase, it proved expedient tocontinue a supply of compressed air even after the starting phase orinitial acceleration when first applying the running thread. Thissubsequent supply of air during normal operation is considerablyreduced, however, as compared to the pressure which the compressed airmust have during the starting phase.

In FIG. 4 there is schematically represented one example of means forthe supply of compressed air under controlled conditions. The box orvessel 17 can be any source of compressed air, for example, a compressedair main such as is commonly installed in most plants. The hollow feedline of axle l fixed to frame 1' is connected over the branched lines 18and 19 and the line T-section 20 with the compressed air source 17. Inthe compressed airline 18 there are installed a pressure adjusting valve21 and also a cut-off valve 22. Likewise, the compressed air line 19also has a pressure adjusting valve 23 and a cut-off valve 24. By way ofexample, the pressure adjusting valve 21 can be set at that pressurerequired during the initial starting or accelerating phase, for exampleat a pressure of 6 atmospheres gauge. On the other hand, the pressureadjusting valve 23 can be set at the pressure required for normalrunning operation, for example at one atmosphere gauge. During theinitial starting phase, the blocking valve 22 is open and the cut-offvalve 24 is closed. After the starting phase is completed, the cut-offvalve 22 is closed while the cut-off valve 24 is opened. The operationof the cut-off valves can be carried out by hand or also electrically orpneumatically in conventional manner. Instead of the two cut-off valves22 and 24, one can also use a single multi-path valve, e.g. alternatingbetween two supply lines.

FIG. 4 further indicates a thread monitor device 25 with a thread sensor26 by which the operation of the cut-off valves 22 and 24 can beautomatically brought about over electric or pneumatic lines 28, 29 and30 in response to the presence or absence of the thread 27 in contactwith the sensor arm or feeler 26. The operation of such valves can alsodepend upon thread tension changing the exact position of the sensor 26as suggested by the broken line position 26. More sophisticated pressurecontrol means for adjusting the pressure inv response to thread tensioncan also be easily adapted to the illustrated thread overrun roller. Theuse of such control arrangements brings about a considerable saving incompressed air and a corresponding saving in electric power.

When operating at high rotational speeds, e.g. 30,000

rpm or more, very little air pressure is required to maintain thecarefully balanced and air-cushioned roller shell turning at about thesame speed as the thread or yarn running in contact therewith. With theadded stabilization of the roller shell in its axial position, anexceptionally smooth running of the thread is achieved, for example,where the thread is being drawn, stretched, twisted, fixed or otherwiseprocessed as it is rapidly transported by conventional nip rolls,winding means or the like in textile apparatus. The thread overrunroller of the invention is thus useful as a driven roller of variousknown types, eg as a separator roller, a thread deflection or guideroller and alone or in combination with other rollers or guide means.

The air outlet channels located in the end face plates of the tubularroller shell, preferably axially adjacent to the inner circumference ofthe shell, are of particular value in quickly accelerating therotational speed of the shell when the thread or yarn is first appliedthereto so as to practically eliminate thread breakage.

The new air-supported thread overrun rollers of the invention are easilyconstructed and readily installed by means of their fixed axle orcarrying shaft on the frames or by supplemental supports on existingtextile machinery. Many variations are possible within the intendedscope of this invention.

The invention is hereby claimed as follows:

1. An air-supported thread overrun roller in textile apparatuscomprising:

a hollow tubular roller shell adapted to be rotatably driven by atransported thread; axle means to carry said roller shell including ashaft segment having an inlet conduit for compressed air extendingaxially into said roller shell and a hollow cylindrical segment ofenlarged diameter connected to said shaft segment so as to extendaxially between the two ends of said roller shell and to provide acompressed air chamber fitting concentrically within said roller shellwith a small annular bearing gap therebetween, the cylindrical wall ofsaid enlarged segment having radial openings to release compressed airinto said bearing gap; and

an annular face plate on said roller shell at either end thereof withthe inner diameter of the face plate being smaller than the outerdiameter of said enlarged axle segment, each-face plate having aplurality of air outlet channels approximately parallel to the rollershell and extending obliquely to the axis of rotation of the shell, saidchannels being arranged at regular intervals on a circle concentric tothe axis of rotation of the shell.

2. A roller as claimed in claim 1 wherein the diameter of said circle onwhich the air outlet channels are arranged is approximately equal to themean diameter of the annular bearing gap located between the enlargedaxle segment and the roller shell.

3. A roller as claimed in claim 1 including a plurality of axialopenings in the end walls of the hollow cylindrical segment of said axleto release compressed air into a gap space between each end wall and theadjacent annular face plate of the roller shell.

4. A roller as claimed in claim 1 wherein said air outlet channels ineach annular face plate follow a curved path scooped in the fashion ofthe blades of an axial turbine.

5. A roller as claimed in claim 1 including means to control the airpressure in said pressure chamber formed by said enlarged axle segment.

6. A roller as claimed in claim 5 including at least two pressure linesconnected to said pressure chamber to supply air at different pressuresand means to selectively switch said pressure chamber to each of saidpressure lines.

1. An air-supported thread overrun roller in textile apparatuscomprising: a hollow tubular roller shell adapted to be rotatably drivenby a transported thread; axle means to carry said roller shell includinga shaft segment having an inlet conduit for compressed air extendingaxially into said roller shell and a hollow cylindrical segment ofenlarged diameter connected to said shaft segment so as to extendaxially between the two ends of said roller shell and to provide acompressed air chamber fitting concentrically within said roller shellwith a small annular bearing gap therebetween, the cylindrical wall ofsaid enlarged segment having radial openings to release compressed airinto said bearing gap; and an annular face plate on said roller shell ateither end thereof with the inner diameter of the face plate beingsmaller than the outer diameter of said enlarged axle segment, each faceplate having a plurality of air outlet channels approximately parallelto the roller shell and extending obliquely to the axis of rotation ofthe shell, said channels being arranged at regular intervals on a circleconcentric to the axis of rotation of the shell.
 2. A roller as claimedin claim 1 wherein the diameter of said circle on which the air outletchannels are arranged is approximately equal to the mean diameter of theannular bearing gap located between the enlarged axle segment and theroller shell.
 3. A roller as claimed in claim 1 including a plurality ofaxial openings in the end walls of the hollow cylindrical segment ofsaid axle to release compressed air into a gap space between each endwall and the adjacent annular face plate of the roller shell.
 4. Aroller as claimed in claim 1 wherein said air outlet channels in eachannular face plate folloW a curved path scooped in the fashion of theblades of an axial turbine.
 5. A roller as claimed in claim 1 includingmeans to control the air pressure in said pressure chamber formed bysaid enlarged axle segment.
 6. A roller as claimed in claim 5 includingat least two pressure lines connected to said pressure chamber to supplyair at different pressures and means to selectively switch said pressurechamber to each of said pressure lines.